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A.2.8 depth 12 interleaver/de˚interleaver, A.2.8 depth 12 interleaver/de-interleaver, Figure a-18. interleaver/de-interleaver – Comtech EF Data SDM-9000 User Manual

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Rev. 4

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A.2.8 Depth 12 Interleaver/De-interleaver

Conceptually, the interleaver is composed of I = 12 branches, cyclically connected to the
input byte stream by the input switch. Each branch is a FIFO shift register, with
depth = 17 x branch index. The cells of the FIFO contain 1 byte, and the input and output
branches are synchronized. For synchronization purposes, the sync bytes and inverted
sync bytes are always routed in branch 0 of the interleaver, corresponding to a null delay.

The de-interleaver is similar in principle to the interleaver, but the branch indexes are
reversed (i.e., branch 0 corresponds to the longest delay). De-interleaver synchronization
is accomplished by routing the first recognized sync byte to branch 0.

Figure A-18 shows the interleaver/de-interleaver block diagram.

17

17x2

17x3

17x11

0

1

2

3

11

0

1

2

3

11

17x11

0

0

17x3

8

8

17x2

9

9

17

10

10

11

11





INTERLEAVER

SYNC BYTE ROUTE

DE-INTERLEAVER

17 BYTE FIFO SHIFT REGISTER

SYNC BYTE ROUTE

Figure A-18. Interleaver/De-interleaver